System for fast macrodiversity switching in mobile wireless networks

ABSTRACT

Fast macrodiversity switching (FMS) dynamically switches radio links used for traffic and control channels for a mobile station among a number of base transceiver stations (BTS) without changing the radio resource, that is, using the same frequency and time slot combination (TDMA) or frequency and spreading code combination (CDMA). The traffic channel switching is under control of zone managers. Each BTS includes a zone manager where a host BTS has its zone manager designated as a host zone manager and other BTSs (assistant BTSs) have their zone managers designated as assistant zone managers. The control by the host and assistant zone managers includes switching down-link signals to and up-link signals from mobile stations among base transceiver stations which include broadcast channels (non-switched) and dedicated (switched) channels. Measurements of the wireless signals are made at macrodiverse locations. Zone managers process the measurements to determine preferred ones of the transceiver stations for particular dedicated channels for a particular mobile station.

BACKGROUND OF THE INVENTION

The present invention relates to the field of mobile wirelesscommunication systems and more specifically to methods and apparatus forcommunication with mobile telephone users (cellular and personalcommunication systems), mobile wireless data communications, two-waypaging and other mobile wireless systems.

In a mobile wireless network, mobile stations (MS) are typically incommunications with one base transceiver station (BTS) through up anddown radio links. Such ground-based radio links suffer from strong localvariations in path loss mainly due to obstructions and line-of-sightattenuation. As MS move from one point to another, their signal pathlosses go through shadow fading fluctuations that are determined, amongother things, by the physical dimension of the obstructions, antennaheights and MS velocity. These variations in path loss, must be takeninto account in the design of the up-link and down-link radio linkresource allocation.

While communicating with a specific host BTS, MS are frequently withinthe communications range of other BTS. Statistically, due to thedistribution of physical obstructions, the shadow fading path lossfluctuations to such other BTS tend to be only weakly correlated withthe path loss fluctuations on the link between the MS to host BTS link.It is therefore possible that a MS, at anyone time and location, has alower path loss to a different BTS than the one it is communicatingwith.

In a conventional wireless network using the GSM standard, the basestation controller (BSC) manages the radio link resources of the BTS.These resources are determined by the number of transceivers installedat the BTS and the number of radio channels anyone transceiver canhandle. For example, in TDMA standards, a radio channel consists of afrequency and a time slot. In CDMA standards, a radio channel isrepresented by a frequency and one of a number of orthogonal spreadingcodes.

A BTS has two principal functions, that of controlling the radio linkswith all MSs within its cell, and relaying traffic between the BSC andthe MSs. Relaying traffic includes receiving down-link traffic from theBSC and broadcasting it to MSs using broadcasters and that of receivingup-link traffic from the MSs using radio receivers called collectors andrelaying it to the BSC.

In a mobile wireless network with a BSC, the BSC controls the assignmentof the radio link resources (including Broadcaster s and Collectors) inthe BTSs as well as the operation of the network, and, through the MSC,provides an interface with the Public Switched Telephone Network (PSTN).For generality, the BTS broadcasting and collecting functions can beconsidered as separate entities. In most existing networks, however,broadcasters (B) and collectors (C) are co-located.

In one example, three base transceiver stations (BTS) include threebroadcasters and three collectors where broadcasters and collectors aretypically but not necessarily co-located. The broadcasters andcollectors have down-links and up-links to the BSC. These links aretypically cabled links such as T1/E1 lines. The connection of theselinks between the broadcasters or collectors with the BSC may bearranged in various configurations such as a star-like pattern, adaisy-chain pattern or in any combination of these or other patterns.

When a connection is setup between a MS and the mobile network, a BSCselects the BTS that has the best radio access to the MS. This setupprocess includes a series of signal transmissions back and forth betweenthe BSC, the BTSs, and the MSs using up-link and down-link radio controlchannels. The setup process results in the assignment of dedicated radiotraffic and control channels for the up-links and down-links forcommunications between the MSs and the BTSs. Once these connections areset-up, user traffic, also called payload, can be transmitted betweenthe MSs and the BSC. While the connection lasts, the BTS/BSC controlsthe operation of the radio traffic channels, including power control,frequency hopping, and timing advance. Also, the BTS/BSC continues touse the radio broadcast channels for operation, maintenance andsignaling with all other MSs in its cell.

Users (MSs) communicate with collectors via control up-links and trafficup-links and with broadcasters via control down-links and trafficdown-links. A particular broadcaster and collector is called the hostbroadcaster and the host collector for a particular MS. Together, theyperform the function of the host BTS for the particular MS.

As MSs move within a cell and as the average path loss between an MS andits serving broadcaster and collector degrades, existing networksreassign the MS to another BTS (with a broadcaster and collector) thathas a lower path loss. This process is called handover or handoff. Priorsystems distinguish between hard and soft handover. During hardhandover, both the control and traffic radio links between the MS andBTS are terminated and new radio links are set-up between the MS and thenew BTS using the radio resources assigned to the new BTS. In case of ahandoff failure, the MS and BTS reestablish the control and trafficradio link as it existed before the handoff was attempted. This hardhandover is used in GSM networks. In CDMA networks, hard and softhandoff is practiced. In soft handoff, the new radio links are setupbefore the old links are terminated (make before break operation). CDMAallows simultaneous communications of a MS with a number of BTS duringsoft handoff.

One technique for maintaining low transmit power during the operation ofa mobile radio link is dynamic power control. It may be applied on boththe up-link and down-link directions or only in one direction, and itmay be performed in an open-loop or closed-loop mode. In open-loop powercontrol mode, the transmit power is determined by system levelparameters. In closed-loop power control mode, the power is dynamicallyset in response to radio link measurements such as distance measurementsbetween the MS and the BTS (as determined by time of arrivalmeasurements), receive signal strength measurements, or error ratemeasurements.

Another known method to improve network performance is the use ofmacrodiversity signal combining (also called aggregation). This methoduses multiple spaced-apart transmitter/broadcasters andcollector/receivers in the BTSs to simultaneously communicate with a MS.The soft handoff practiced in CDMA is such an example. On the down-link,the signal is transmitted from multiple spaced-apart broadcasters usingdown-link traffic channels. These multiple signals are received by theMS (for example using a rake receiver in CDMA), and combined, to providea processed signal with a higher level of confidence. On the up-link,multiple spaced-apart receivers/collectors receive the signaltransmitted by the MS on up-link traffic channels. These multiplereceive signals are then transported to a central location and processedto provide a processed signal with a higher confidence level then any ofthe individual signals would provide. One disadvantage of macrodiversitycombining, when used on the up-link, is the added backhaul associatedwith transporting the receive signals from multiple collectors to onecentral location.

While many different wireless networks have been proposed, there is aneed for improved wireless networks that achieve the objectives ofimproved performance and higher density of MSs.

SUMMARY

The present invention is a method and apparatus for fast macrodiversityswitching (FMS). The fast macrodiversity switching dynamically switchesradio links used for traffic and control channels for a mobile stationamong a number of base transceiver stations (BTS) without changing theradio resource, that is, using the same frequency and time slotcombination (TDMA) or frequency and spreading code combination (CDMA).

The channel switching is under control of zone managers. Each BTSincludes or is otherwise associated with a zone manager where a host BTShas its zone manager designated as a host zone manager and other BTSs(assistant BTSs) have their zone managers designated as assistant zonemanagers.

The control by the host and assistant zone managers includes switchingdown-link signals to and up-link signals from mobile stations among basetransceiver stations which include broadcast channels (non-switched) anddedicated (switched) channels. Measurements of the wireless signals aremade at macrodiverse locations. Zone managers process the measurementsto determine preferred ones of the transceiver stations for particulardedicated channels for a particular mobile station. Preferred ones ofthe transceiver stations are dynamically selected to provide thededicated channels for the mobile stations separately from thetransceiver stations providing broadcast channels for the mobilestations. The measurements are made on the up-link signals from themobile stations. The dedicated channels are switched as frequently as asignal change time which can be as frequent as the frequency of themeasured signals, for example, the frame rate of the up-link signals.The change time is typically less than 1 second for mobile stations.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following detailed description inconjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a wireless network formed of multiple base transceiverstations (BTSs) and multiple associated zone managers (ZMs).

FIG. 2 depicts a wireless network formed of multiple base transceiverstations (BTSs) and multiple zone managers (ZMs) where traffic andcontrol communications are between a host BTS and an MS under control ofa host zone manager and assistant zone managers for other BTS.

FIG. 3 depicts a wireless network formed of multiple base transceiverstations (BTSs) and multiple zone managers (ZMs) where control andtraffic communications have been switched among host and assistant BTSunder control of a host zone manager and assistant zone managers.

FIG. 4 depicts further details of the host/assistant wireless networksof FIG. 1 through FIG. 3 with host and assistant zone managers.

FIG. 5 depicts a representation of the transceivers which form a part ofeach of the base transceiver stations of FIG. 4.

FIG. 6 depicts a schematic block diagram of a zone manager.

FIG. 7 depicts a representation of the measurement signal processing ofa zone manager.

FIG. 8 depicts a representation of signals used in generating themeasurement information used in the FIG. 7 processing.

FIG. 9 depicts a representation of signal timing for generatingmeasurement signals in a GSM system.

FIG. 10 depicts a representation of signal timing for generatingmeasurement reports based upon the measurement signals of FIG. 9.

FIG. 11 depicts a wireless network formed of multiple base transceiverstations (BTSs) and multiple zone managers (ZMs) where controlcommunications are between a host BTS and an MS while trafficcommunications are between assistant BTSs, all under control of a hostzone manager and assistant zone managers.

FIG. 12 depicts a wireless network formed of multiple base transceiverstations (BTSs) and multiple zone managers (ZMs) where controlcommunications are between a host BTS and an MS while trafficcommunications are between assistant BTSs, different than in FIG. 11,all under control of a host zone manager and assistant zone managers.

DETAILED DESCRIPTION

FIG. 1 depicts a mobile wireless network 101 including base transceiverstations 12 that have radio down-links and radio up-links to a basecontroller 16. These links are typically cabled links such as T1/E1lines. The base controller 16 is formed of a base station controller(BSC) 16-1 and a Serving GPRS Support Node (SGSN) 16-2. The BSC 16-1controls the assignment of the radio link resources and the operation ofthe network and has an interface through the mobile switching center(MSC) 117, with the Public Switched Telephone Network (PSTN) 121 ofnetworks 123. The SGSN 16-2 is primarily responsible for mobilitymanagement, detects mobile stations in the local area for thetransmission and receipt of packets. Additionally, it locates andidentifies the status of mobile stations and gathers crucial callinformation. The SGSN operates with standard network interfaces andcapabilities for the transport of IP using Frame Relay and ATM overphysical interfaces.

In FIG. 1, the base controller (BC) 16, including the base stationcontroller (BSC) 16-1 and the SGSN 16-2, are part of the base stationsystem (BSS) 115. The BSC 16-1 communicates with the base transceiverstations (BTS) 12 within the cells 111 of the wireless network 101. Thecells 111-1, 111-2 and 111-3 are shown in expanded detail to include theBTS 12-1, 12-2 and 12-3, respectively, and the associated zone managers(ZM) 13 including ZMs 13-1, 13-2 and 13-3, respectively. The ZMs 13-1,13-2 and 13-3 are interconnected to form a zone network that controlsthe macrodiversity switching of the channels among the BTSs 12. The zonenetwork interconnecting the zone managers 13 can be in any formincluding mesh, daisy-chain, star or otherwise.

In FIG. 1, the MSs 4 are mobile within the cell region 111 and can move,for example, between the cells 111-1, 111-2 and 111-3. As MSs 4 move inthe region 111, the ZMs 13 operate to implement the fast macrodiversityswitching of the channels.

In FIG. 1, the control functions of the BC 16, the BTS 12 and the ZM 13collectively are part of a region controller 115 which controls theoperation of the wireless network 101.

In FIG. 1, the MSC 117, part of a network and switching subsystem (NSS)106, connects to the PSTN 121 within the networks 123. Similarly, theSGSN 16-2 of the BC 16 connects directly to the internet 120 of thenetworks 123.

In the wireless mobile network 111 of FIG. 1, when a connection to a BTSis setup for MS, the BSC selects the BTS that has the best radio accessto the MS as host BTS. This setup process includes a series of signaltransmissions back and forth between the BSC, the BTSs, and the MS usingup-link and down-link radio control channels, and results in theassignment of dedicated radio traffic and control channels for theup-link and down-link between the MS and the BTS. Once this connectionis set-up, user traffic is transmitted between the MS and the BSC. Whilethe connection lasts, the BTS/BSC controls the operation of the radiotraffic channels, including power control, frequency hopping, and timingadvance on dedicated control channels, while it continues to use theradio broadcast channel for operation, maintenance and signaling withall the other MSs in the cell.

In the wireless mobile network 111 of FIG. 1, broadcast channels anddedicated channels are separate. Dedicated channels include control andtraffic channels specific to an MS. Broadcast channels are used forsignaling and control messages shared by all MSs within the cell,including MSs that are not in use. Broadcast and dedicated channels arecarried over radio links. Traffic channels are used to transport usersignals also called payload which can be voice or data. To ensure thatall MSs within the cell have access to the control signals, the radiolink for the broadcast channel is designed to be very reliable by usingrobust coding and modulation techniques and a high transmit power level.

In the wireless network 111 of FIG. 1, dedicated radio links serveindividual MSs and are at times operated at lower power levels. Forinstance, MSs close to a BTS do not require large transmit power levelsand are operated at the minimum level meeting the link qualityrequirements. The reason for reducing power is to conserve radio bandresources to enable reuse of radio resources in as many cells in thenetwork as possible. MSs sharing up-link radio resources generateco-channel interference at their respective BTSs and BTSs sharingdown-link radio resources generate co-channel interference at theirrespective MSs.

Shadow fading imposes large fluctuations on the path loss between aparticular MS moving in a cell and its serving BTS. At times when thepath loss to the BTS is high, a high transmit power is used to maintainthe quality of service. At such times, it is likely that the path lossbetween the particular MS and another BTS is lower because shadow fadingeffects between a MS and different BTSs are not highly correlated.Therefore, such other BTS can communicate traffic and/or control signalswith the particular MS using lower up-link and down-link power levels.By switching the traffic and/or control channel over to such other BTS,the contribution of the particular radio link to the interference levelin the network for other MS-BTS links that use the same radio resourcesis reduced. When such switching is implemented for many radio links in anetwork, a larger number of links can be operated in the networkincreasing network capacity without adding radio bandwidth.

To take advantage of the de-correlation of shadow fading effects, a BTSwith the lowest instantaneous path loss for communicating up-link anddown-link channels to a particular MS is selected using fastmacrodiversity switching. In order to implement the operation, host andassistant BTSs are employed in some embodiments. The host BTS is the BTSthat is selected by the BSC 16-1 during connection set-up forcommunications with a particular MS 4. The host BTS remains in controlof the particular MS 4 via its broadcast channel until a handover iscarried out. The dedicated channels with the particular MS are routedoriginally through the host BTS. When another BTS with a lower path lossbecomes available, traffic and control channels are routed through suchother BTS, which is designated as the assistant BTS for particularchannels. As an MS moves through the cell, and as its path andshadow-fading losses change, the dedicated channels are switched among anumber of BTSs in the network, including the host BTS. This channelswitching continues until the path loss between the particular MS andthe host BTS becomes too high and a handover of the broadcast anddedicated channels is executed.

In the fast macrodiversity selection (FMS) process described, the radioresource used for the a dedicated channel (frequency, time slot, code)for the host BTS is not changed. FMS is therefore different from thehandover process where both, the broadcast and dedicated channels areswitched from radio resources assigned to the old BTS to radio resourcesassigned to the new BTS in accordance with a frequency reuse plan.

The time scale of the fast macrodiversity switching process is fastrelative to handover timing. Fast macrodiversity switching operates inone embodiment, for example, at switching speeds less than one secondand in the range of 0.02 seconds to 0.25 seconds. In one implementation,the switching speed is determined by the rate at which the networkprovides radio link measurements, the time behavior of shadow fading andthe MS velocity. In practical implementations, the switching speed maybe constant or may be variable.

In fast macrodiversity switching operation of FIG. 1, it is assumed forpurposes of explanation that BTS 12-1 and ZM 13-1 form the host basestation (BS) 2-1 for some particular MS. It is also assumed that BS 2-2and BS 2-3 are assistant BSs available to transmit and receive channelson a radio resource assigned to the host BS 2-1. Since every BS(including a BTS and a ZM) in the network can be both a host BS for someMSs and an assistant BS for other MSs, each such BS has collector andbroadcaster resources that can be tuned to any frequency and time slotavailable in the network.

In one embodiment, additional broadcaster and collector resources areinstalled in BTSs over what normally are used in the BTSs. Theseadditional resources can be solely dedicated to perform the assistant BSfast macrodiversity switching functions under the control of a zonemanager (ZM) 13. In one embodiment, the use of the original radioresources in the BTS are controlled by the BSC. In another embodiment,the original broadcasters and collectors of a BTS and any additionallyinstalled broadcasters and collectors form a common radio resource pool.In this common pool implementation, all resources in the pool may beused to perform the host and the assistant BTS functions. This commonpooling implementation makes better use of the available transceiver(broadcaster and collector) resources. Control of this resource poolmaybe with the BSC 16-1 for the host BTS function and with the ZMs forthe assistant BTS functions, or control of all resources may be witheither the BSC 16-1 or the ZMs 13.

In FIG. 2, the host BTS (_(h)BTS) 12-1 and the corresponding host ZM(_(h)ZM) 13-1 form the host base station (_(h)BS) 2-1 for the particularone MS 4 shown in FIG. 2. The host _(h)BTS 12-1 and the MS 4 in theinstance of FIG. 2 operate essentially as a standard GSM system.Communications between the _(h)BTS 12-1 and the MS 4 include the up-linktraffic, T_(U), on link 11 _(U) and down-link traffic, T_(D), on link 11_(D). The control channels include the down-link control, C_(D), on link10 _(D1,2), and the up-link control, C_(U), on link 10 _(U1,2). Thedown-link control channel, C_(D), has two components, a down-linkbroadcast control channel on link 10 _(D1) and a dedicated down-linkcontrol channel on link 10 _(D2). The up-link control channel, C_(U),has two components, an up-link control channel on link 10 _(U1) and adedicated up-link control channel on link 10 _(U2). Although MS 4 isunder control of the host _(h)BTS 12-1, assistant BTSs, including afirst assistant _(a1)BTS 12-2 and a second assistant _(aa)BTS 12-3,associated with the assistant zone managers _(a1)ZM 13-2 and _(aa)ZM13-3, respectively, also are available for communications with MS 4. The_(h)ZM zone manager 13-1, _(a1)ZM zone manager 13-2 and _(aa)ZM zonemanager 13-3 are interconnected via link 14 to form the microdiversityswitching network for controlling the fast switching of the dedicatedchannels among the _(h)BTS 12-1, _(a1)BTS 12-2 and _(aa)BTS 12-3. Anynumber of BTSs 12 and ZMs 13 can be included in the channel switchingnetwork of FIG. 2.

In FIG. 3, the _(h)BTS 12-1 and the corresponding _(h)ZM 13-1 are thehost BTS and the host ZM forming the host BS 2-1 for the MS 4. Therelationship between the BTS 12-1 and the MS 4 of FIG. 3 is not likethat for a standard GSM system. In FIG. 3, the traffic communication ison dedicated channels that have been switched to be between theassistant _(a1)BTS 12-2 in the assistant BS 2-2 and the MS 4 for theup-link traffic, T_(U), on link 11 _(U) and has been switched toassistant _(aa)BTS 12-3 in the assistant BS 2-2 for the down-linktraffic, T_(D), on link 11 _(D). One part of the control channels, thedown-link control, C_(D1) on link 10 _(D1), is a broadcast channel andthat broadcast channel remains between host _(h)BTS 12-1 and MS 4. Theother part of the control channels, dedicated down-link control, C_(D2),on link 10 _(D2) and the up-link control, C_(U2), on link 10 _(U2), areswitched to the assistant _(aa)BTS 12-3 and _(a1)BTS 12-2, respectively.Although MS 4 is under control of the host _(h)BTS 12-1 via thedown-link broadcast channel, the assistant BTSs including _(a1)BTS 12-2and _(aa)BTS 12-3, associated with the assistant zone managers _(a1)ZM13-2 and _(aa)ZM 13-3, directly carry the payload and the dedicatedcontrol channels with MS 4. The FIG. 3 embodiment demonstrates theswitching of both traffic and control channels in the fastmacrodiversity switching process.

In FIG. 4, there are n users, MS 4, namely MS₁ 4-1, MS₂ 4-2, MS₃ 4-3, .. . , MS_(n) 4-n. User MS₁ is shown communicating with _(h)BTS 12-1 inthe host _(h)BS 2-1 via control link 10-1 including down-link control10-1 _(D1) and a control up-link 10-1 _(U1). The user MS₁, iscommunicating with a traffic up-link 11-1 _(U) and a control up-link10-1 _(U2) to assistant _(a1)BTS 12-a1 in base station 2-a1 and with atraffic down-link 11-1 _(D) and control down-link 10-1 _(D2) toassistant ₃BTS 12-3 in base station 2-a1 2-3. The ₁BTS 12-1 is the hostBTS for MS₁. Similarly, user MS₂ communicates with ₂BTS in BS 2-2 viacontrol and traffic links 10-2 and 11-2, respectively. The ₂BTS 12-2 isthe host BTS for MS₂. User MS₃ 4-3 communicates with ₃BTS 12-3 in BS 2-3via control and traffic links 10-3 and 11-3, respectively. The ₃BTS 12-3is the host BTS for MS₃ and the _(a1)BTS and ₃BTS are assistant BTS foruser MS₁.

In FIG. 4, the BSC 16-1 in the base controller (BC) 16 communicates overan Abis interface, including the up-link and down-link control signals5-1 and the up-link and down-link traffic signals 6-1, with the ₁BTS12-1 in base station 2-1. Similarly, the BSC 16-1 communicates over anAbis interface, including the up-link and down-link control signals 5-nand the up-link and down-link traffic signals 6-n connected to the_(a1)ZM zone manager 13-a1 in the _(a1)BS base station 2-a1.

In FIG. 4, the user MS₁ 4-1 communicates with its host ₁BTS 12-1 whichis part of the host base station (_(h)BS) 2-1. Also included in the hostbase station 2-1 is the zone manager ₁ZM 13-1 which serves as the hostzone manager for the user MS₁.

In FIG. 4, the base station _(a1)BS base station 2-a1 is an assistantfor user MS₁, and includes the _(a1)ZM zone manager 13-a1 and theassistant _(a1)BTS 12-a1. The base station 2-a1 is the host base stationfor the user MS_(n) and is an assistant base station for the basestation 2-1 that is the host base station for the user MS₁ 4-1. In the_(a1)BS base station 2-a1, the zone manager 13-a1 is positioned in theAbis interface connection between the BSC 16-1 and the _(a1)BTS.

The entities that control the fast macrodiversity switching process arezone managers (ZMs) 13. In the FIG. 4 implementation, one ZM 13 isinstalled in each cell and is associated with a corresponding BTS 12 forthat cell.

In FIG. 4 the zone managers ₁ZM, ₂ZM, ₃ZM, . . . , _(a1)ZM form the zonemanager network 55 for controlling the fast macrodiversity switching ofthe dedicated channels. In the embodiment of FIG. 4, zone manager ₁ZMconnects to zone manager ₃ZM via the link 14 _(1/3), the zone manager₁ZM connects to the zone manager ₂ZM via the link 14 _(1/2), the zonemanager ₃ZM connects to the zone manager ₂ZM via the link 14 _(3/2) andthe zone manager ₁ZM connects to the zone manager _(a1)ZM via the link14 _(1/a1). In some embodiments, the zone manager is separate from theBTS as shown in the base station 2-1 of FIG. 4 with an interface at 15-1between the ₁BTS and the ₁ZM. In other embodiments, the ZM is in theAbis interface connection as shown in the _(a1)BS base station 2-a1. Instill other embodiments, the ZM is fully integrated with the BTS. Theparticular implementation selected for the ZM is a matter of designchoice.

In FIG. 4, broadcasters and collectors are included as a common entityin each BTS 12. In some wireless networks broadcasters and collectorsfor the same BTS are separated by macro-diverse distances and aretherefore considered separately. The usual configuration where theup-link and down-link path losses typically are highly correlated hasbroadcasters and collectors co-located at the BTS.

FIG. 4 represents a snap shot of an fast macrodiversity switchingimplementation for one particular period of time analogous to theconfiguration of FIG. 3. Any of the MS, for example MS₂ or MS₃ can alsocommunicate with different BTS on their dedicated channels at any timein the manner suggested in FIG. 2 through FIG. 12. The FIG. 4 embodimenthas distributed zone managers. In another embodiment, the zone managerfunction can be centralized and located, for example, in the BSC 16-1.As shown in FIG. 4, the zone manager may be integrated or connected withthe BTS, or located on the Abis link.

FIG. 5 depicts a representation of the transceivers 60 which form a partof each of the base stations 2 of FIG. 4. In FIG. 5, the transceivers 61and 62 each include a co-located broadcaster (B) and collector (C). Whenemploying SDMA protocols, the transceivers 61 and 62 in some embodimentsuse smart antennas. The transceivers 61-1, . . . , 61-T₁ are thetransceivers that are present in an ordinary GSM installation. Thetransceivers 62-1, . . . , 62-T₂ are the transceivers that are added inconnection with fast macrodiversity switching. The transceivers 61 and62 of FIG. 5 can be considered as a single pool allocated for anyfunction in a base station 2 or can remain segregated so that thetransceivers 61-1, . . . , 61-T₁ are allocated for ordinary base stationoperation and the transceiver 62-1, . . . , 62-T₂ are allocated by zonemanagers only for macrodiversity switching functions.

The function of each ZM 13 is to enable fast macrodiversity switching inthe mobile wireless network. Its basic components are shown in FIG. 6.They are a macrodiversity processor (MDP) 20, control means 75 includingresource manager, (RM) 21 and airlink controller (AC) 22, and interfacemeans 76 including ZM-ZM interface manager 23 for the ZM-to-ZM links 14and ZM-BTS interface manager 24 for the BTS-to-ZM transceiver link 15.The control means 75 issues broadcaster commands for controlling thedown-link signals to each of selected ones of mobile stations andcollector commands for controlling the plurality of macro-diversecollectors for changing the up-link signals for each of other selectedones of the mobile stations. Similar to the roles of host and assistantBTS, a distinction is made between host ZM and assistant ZM. A host ZMcontrols the fast macrodiversity switching services to the set of MSwithin the cell of the host BTS. An assistant ZM 13 provides fastmacrodiversity switching services to the host ZM 13 for the same set ofMS. Therefore, the role of a particular ZM 13 depends on the location ofMS in the network. Any ZM 13 is a host ZM for the particular MScontrolled by the host BTS and an assistant ZM for all other MSs.

In FIG. 6, the macrodiversity processor (MDP) 20 is a processor forprocessing the measurement and control signals used in controlling thefast macrodiversity switching of dedicated channels. The resourcemanager (RM) 21 functions to keep track of and control all of theresources, including BTS broadcasters and collectors, available used andunused channels and links, and other resources in the wireless networkneeded for fast macrodiversity switching. The airlink controller (AC) 22is responsible for controlling the radio links among the BTSs and MSsvia assistant ZMs and ZM-ZM links 14. The ZM-ZM interface manager 23controls the ZM-to-ZM interface links 14 among zone managers 13 andsupervises the zone manager network 55 of FIG. 4 for controlling thefast macrodiversity switching of dedicated channels. The ZM-BTSinterface manager 24 functions to control the ZM-BTS link 15 between theZM and BTS of a base station (BS).

The resource manager (RM) 21 within the ZM 13 controls the radioresources for fast macrodiversity switching services. In a typical BTS,a number of transceivers (see 61-1, . . . , 61-T₁ in FIG. 5) areinstalled to provide the radio links to an MS. In a BS 2 of FIG. 4,additional transceivers, called guest transceivers (see 61-1, . . . ,61-T₂ in FIG. 5) are installed. These guest transceivers provide theadditional radio resources useful in implementing fast macrodiversityswitching. In the basic implementation, as discussed above, radioresources provided by the guest transceivers are managed by the RM 21,while the allocation of the host transceiver radio resources remainsunder BSC 16-1 control. The RM 21 keeps track of all used and idle hostand guest radio resources available in its host BTS including thetransceivers of FIG. 5. It receives radio link information, for examplein the form of measurement reports and other information, eitherdirectly from its corresponding ZM or from other ZM in assistant BTSsvia the ZM-to-ZM links 14. Since the transceiver stations communicateover a region containing one or more zones and the measurements arereceived from one or more collectors in the transceiver stations, themeasurements from collectors include radio link conditions between amobile station and the one or more collectors where the radio linkinformation incorporates radio link conditions such as path loss,forward error rates, and carrier-to-interference ratio. The RM 21 in thehost ZM also tracks radio resource usage in all assistant BTSs throughcommunications with the RMs in the assisting BTSs. The RM 21 in the hostBTS stores and updates this information in a radio resource data base(DB) 25. During installation, all RMs are initialized with the identityof those BTSs in the network that are candidates for becoming assistantBTSs and the specific radio resources available in these BTSs.Alternatively, the ZM's may communicate with each other to determine theidentity of assistant BTSs both at setup time and periodically duringoperation. When the MDP 20 requests a radio resource, the RM 21 checksthe priority level of the request and the availability (in location,frequency, time slot or spreading code) of a radio resource suited tomeet the request as stored in DB 25. If no such resource is available,or if the priority level of the request is insufficient, the request isdenied. Otherwise, the radio resource is released and the data base 25is updated accordingly. The assignment of the radio resource is alsocommunicated to the other RMs in other ZMs for updating their respectivedata bases.

To perform the fast macrodiversity switching function, the ZM usesalgorithms to track information in real time and to provide resourcecontention resolution, for the host BTS as well as for all assistantBTS, for each MS. The ZM controls the outgoing information flow on thelinks 14 to other ZMs including the bandwidth resources of the links 14between host BTS and assistant BTSs. The process of controlling theresources of the links 14 is analogous to the process of controlling theradio resources.

In one implementation, the host and guest transceivers form a pool ofradio resources for assignment by both the ZM and the BSC, or by the ZMalone. In the latter case, the ZM is responsible for tracking andassigning radio resources for the host cell, both for normal traffic andfor the fast macrodiversity switching service.

The MDP 20 provides several functions. One function of MDP 20 is toextract radio link quality measurements over the ZM-to-BTS data link forall the MSs in the host cell. These measurements are processed todetermine when a need for fast macrodiversity switching services existsand what priority level is appropriate. Another function of the MDP 20is to determine which of the assistant BTSs is best suited to providethe service. This function is done by transfer of measurements from theMDP 20 in one ZM 13 to other MDPs in the other ZMs. The MDP 20 thensends requests with a priority level for an appropriate radio resourceand for link bandwidth to the RM 21. If the resource is available, thedown-link traffic data is sent to the ZM-BTS interface manager 24 fortransmission to the assistant BTS. Similarly, the AC 22 is instructed tomake the radio resource available with configuration for fastmacrodiversity switching. Similarly, on the up-link, the assistant BTSis instructed to receive up-link traffic from the MS on the identifiedradio link and to forward the traffic to the host BTS.

Another function of the MDP 20 is to monitor the control channelsrelayed by the host BTS. In the event of a MS or BSC originatedhandover, the MDP 20 may intervene with the handover process andcontinue fast macrodiversity switching services, or discontinue fastmacrodiversity switching services with the MS 20 controlling thehandover.

A further function of the MDP 20 is the control of the fastmacrodiversity switching speed. Depending on the shadow fadingstatistics, as determined by the radio link measurements, the MDP 20uses internal speed algorithms to optimize the fast macrodiversityswitching speed.

Another function of the MDP 20, in some embodiments, is to provideaggregation services. These aggregation services are similar to fastmacrodiversity switching functions and are performed using the ZMs. Inaggregation, more than one transceiver is communicating with aparticular MS. On the down-link, this operation consists of transmittingsignals from more than one broadcaster to the particular MS using thesame radio resource. This service is only possible with MSs that havethe ability to receive the signals received separately and process thereceived signals to obtain a resulting down-link signal with a higherconfidence level than any of the individual down-link signals. On theup-link, aggregation consists of receiving the particular MS signal inthe collector of the host BTS, together with the MS signal withcollectors located at assistant BTSs, transmitting these up-link signalsto the MDP 20 in the host BTS via the ZM-to-ZM data links 14, andprocessing these signals to form a resulting up-link signal with ahigher confidence level than any of the individual up-link signals.

The AC 22 provides the ZM 13 with the ability to set certain parametersof the up-link and down-link radio links between a guest transceiver anda MS using macrodiversity services. By way of example, the AC 22 has theability to determine and set transmit power settings. When a guesttransceiver is assisting another BS to provide a radio link to a MS, theAC 22 informs the transceiver providing the radio resource for the fastmacrodiversity switching service of the initial power level. Similarly,the AC is responsible for timing advance and for synchronizing the datatransfer on the up-link and down-link during fast macrodiversityswitching operations.

The ZM-to-ZM links 14 of FIG. 6 are used in fast macrodiversityswitching. Referring to FIG. 1, a hierarchical control structure routestraffic between the PSTN 121 via a mobile switching center (MSC) 117 toan MS 4 through one of a number of BSCs (like BSC 16-1 in FIG. 1) andthen through one of an even larger number of BTSs 12. With fastmacrodiversity switching, however, up-link and down-link traffic is alsorouted between BTSs 12 through operation of the zone managers 13. Inaddition to routing traffic for fast macrodiversity switching services,the ZM-to-ZM links 14 are used in the control of the fast macrodiversityswitching process. This fast macrodiversity switching control functionis distributed among the ZMs. The data exchange between ZMs forproviding each other with the measurement, resource and otherinformation needed for fast macrodiversity switching services, iscarried over the ZM-to-ZM links 14. The control of this information flowis managed by the RM 25 in each of the ZMs, but the formatting,organization of the data and the actual transmission is controlled byZM-ZM interface mangers 23 in a zone manager at each end of a ZM-to-ZMlink 14.

In FIG. 6, the ZM-ZM interface manager 23 provides latency control andbandwidth management across the ZM-to-ZM links 14. The ZM-ZM interfacemanager 23 also contributes to fast macrodiversity switching decision bymonitoring the link utilization and quality of service over the ZM-to-ZMlinks 14.

The ZM-to-BTS link 15 is used to transport voice or data traffic,connection setup information, control information (for MDP, RM, and ACfunctions) and fast macrodiversity switching traffic forwarded to otherZMs and BTSs. The control of this data flow in both directions isformatted and organized by the ZM-BTS interface managers in each zonemanager.

The benefit provided by fast macrodiversity switching to mobile networkoperators over or in addition to using power control, frequency hopping,smart antennas and repeaters, is based on the fact, that all dedicatedchannels are operated, at all times, using the radio link with thelowest available path loss. This operation makes it possible to set theMS and the BTS transmitters at the lowest possible power levels. Whenimplemented in the entire network, this leads to a reduction in theinterference level, allowing operators to change the frequency reusepatterns and increase network capacity and throughput.

In FIG. 7, the steps by which measurement signals are generated andprocessed to form the processor information for controlling the fastmacrodiversity switching are shown. FIG. 7, as implemented in FIG. 6, isa measurement unit and there is one for each zone manager. The MS U_TCHsignal broadcast step 71 represents the traffic channel (TCH) up-linksignals periodically generated by a typical mobile station MS in thewireless networks described in FIG. 1 through FIG. 4. Each zone managerwithin range detects these signals from a particular MS and processesthe received U_TCH signal to form a measurement report. The measurementreport includes information about the MS-BTS radio up-link path loss andthe received signal quality. In particularly, a host base station,_(h)BS, makes a first measurement, Measure-1, indicated by the step72-1. A first assistant base station, ₁BS, makes a second measurement,Measure-2, indicated by the step 72-2. Finally a M^(th) base station,_(m)BS, makes an M^(th) measurement, Measure-M, indicated by step 73-M.

In FIG. 7, the measurements from the steps 72-2, . . . , 72-M are allforwarded via the assistant zone managers 13 over links 14. (See FIG. 2through FIG. 7) to the host zone manager _(h)ZM. The measurement reportsfrom steps 72-1, . . . , 72-M are derived, for example, from the up-linkTCH signal transmission by a particular one of the MSs. In addition, tothe TCH measurement reports, the measurement report “MS_(D—)Meas.Report” is also received by the host zone manager, _(h)ZM, and is inputto the _(h)ZM process step 73 for use in measurement signal processing.The measurement signals are processed in step 73 to provide outputs tothe control step 74 which determines what control action should betaken. The processing steps of FIG. 7 are performed by themacrodiversity processor 20 in cooperation with the other components inthe ZM 13 of FIG. 7.

In FIG. 8, signals which are generated in the wireless network of FIG. 1are shown. The different components generating or receiving signalsinclude one particular MS and for that particular MS, a host basestation, _(h)BTS, a first assistant base station, _(a1)BS, a secondassistant station _(a2)BS, a host zone manager, _(h)ZM, a firstassistant zone manager, _(a1)ZM, and a second assistant zone manager,_(a2)ZM. In operation of a wireless network, a transmitted TCH signal(D_TCH) is received by the particular MS. The MS, after receiving anappropriate number of D_TCH signals, generates a measurement report,MS_(D—)Meas. Report, which is transmitted on an up-link slow associatedcontrol channel (U_SACCH) to the host _(h)BTS. The _(h)BTS in turntransmits the measurement report, MS_(D—)Meas. Report, to the host zonemanager, _(h)ZM.

During the down-link operations that generate the MS_(D—)Meas. Report,the MS is transmitting an up-link TCH signals, U_TCH. Each transmittedTCH signal from the MS is detected by the base transceiver stationswithin range including, in the FIG. 8 example, the _(h)BTS, the _(a1)BTSand the _(a2)BTS. Each BTS generates a measurement report including theU_(h—)Measurement_Report, U_(a1)Measurement_Report and theU_(a2—)Measurement_Report in response to a number of U_TCH transmittedfrom the particular MS. Each of these measurement reports are directedto the corresponding zone manager including the _(h)ZM, _(a1)ZM and a₂ZMzone managers, respectively. Each assistant zone manager, namely _(a1)ZMand _(a2)ZM, forward the measurement reports to the host zone manager,_(h)ZM. As indicated in FIG. 7, the _(h)ZM process 73 processes each ofthe measurement reports.

In FIG. 9, a further representation of signals in a GSM system areshown. For example, the 800-900 MHz wireless spectrum, the GSM frequencychannels occur in 25 MH_(z) bands including and the channels CH₀, CH₁,CH₂, . . . , CH_(c), . . . , CH_(C). Each one of the channels, such astypical channel CH_(c), includes a 200 KHz band which represents atypical GSM frequency channel with a center frequency ω_(c). Each GSMfrequency channel is further divided into eight time slots in a GSM TDMAframe including the time slots TS₀, TS₁, . . . , TS₇. The GSM TDMA frameis (approximately 60/13×10⁻³ second). Each set of four frames forms ablock. Each successive group of 26 GSM TDMA frames forms a superblockand superblocks SB0, SB1, SB2 and SB3 are shown in FIG. 9. Foursuccessive superblocks, such as SB0, . . . , SB3, together form oneSACCH multiframe. After a set of three blocks, a SACCH frame occurs sothat there are two SACCH frames, at F12 and F25, in each superblock, SB.Of these two SACCH frames, one is usually idle and the other containsthe SACCH data including down-link measurement reports.

In FIG. 9, the TCH signals, U_TCH, for any particular MS are generatedin the time slot for the MS which occurs once for each TDMA frame at theTDMA frame rate. Accordingly, as shown in FIG. 9, U_TCH signals for aparticular MS are generated approximately each 4.6 ms at the TDMA framerate. Therefore, each block of four frames, for example frames F0, F1,F2 and F3, generates four U-TCH signals in a block period ofapproximately 18.5 ms. In the next frame after three blocks of frames, aSACCH signal is generated and is indicated in FIG. 9 as the U_SACCHsignals that occur approximately every 60 ms. Although a U_SACCH signalis generated every 60 ms as indicated in FIG. 9, the actual measurementdata determined by any particular MS is interleaved for transmissionamong eight SACCH frames. Accordingly, the measurement data for anyparticular measurement made by a particular MS is not available untilafter four superblocks, such as SB0, SB1, SB2 and SB3 in FIG. 9, arereceived. Each superblock is approximately 120 ms so that the foursuperblocks require 480 ms. Accordingly, the MS_(D—)Meas. Report, asshown in FIG. 7 is only available once every 480 ms while the U_TCHmeasurement signals are available approximately every 4.6 ms.

In FIG. 10, an example of fast macrodiversity measurement and switchingoperations is shown for the measurement signals of FIG. 9. The host_(h)BS and the assistant _(a1)BS, . . . . , _(aa)BS (see FIG. 1 throughFIG. 4) each measure signal quality at a measurement signal rate, 1/T,that is, every time a dedicated up-link burst (U_TCH, FIG. 9) isreceived. In FIG. 9, the U_TCH have the burst period, T, equal toapproximately 4.6 ms. In FIG. 10, the burst period, T, occurs at timest0, t1, . . . , t16, . . . when the U_TCH or U_SACCH bursts aretransmitted by an MS. In the embodiment of FIG. 10, each burst receivedfrom an MS at about every T=4.6 ms is measured by the ZMs for signalstrength or other quality parameter at the measurement signal rate. TheZMs integrate each of these measurements over an integration length (IL)using a sliding time window to form an integrated measurement report andoutput these integrated measurement reports at an output rate (OR). TheIL and OR values are variable numbers controlled either by the ZMaffiliated with the BS making the measurements or centrally, forexample, by the _(h)ZM. The values of OR and IL can be fixed for allcalls or can be individually adaptive in response to specific MSconditions such as shadow fading time scale and mobile speed for eachcall in progress.

FIG. 10 shows two examples of integrated measurement reporting basedupon measurement signals occurring at the measurement signal rate of1/T. In the upper example, integration is over four consecutive burstmeasurements of period T so that IL=4 and reports are generated at theburst rate so that OR=1/T. In the lower example, integration is over sixconsecutive burst measurements so that IL=6 and reports are generated atthe rate of every three bursts so that OR=⅓T.

In the example of FIG. 10 where OR=1/T and IL=4T, at times t0, t1, t2and t3, each U_TCH signal is detected and measured by the host andassistant BTS and each provides an integrated measurement report,namely, the U_(h—)Measurement_Report, the U_(a1—)Measurement_Report andthe U_(a2)Measurement_Report, as indicated in FIG. 8, at time t4.Similarly, at times t1, t2, t3 and t4, each U_TCH signal is detected andmeasured by the host and assistant BTS and each provides an integratedmeasurement report, namely, the U_(h—)Measurement_Report, theU_(a1—)Measurement_Report and the U_(a2—)Measurement_Report, asindicated in FIG. 8, at time t5. Similarly, at times t2, t3, t4 and t5,each U_TCH signal is detected and measured by the host and assistant BTSand each provides an integrated measurement report, namely, theU_(h—)Measurement_Report, the U_(a1—)Measurement_Report and theU_(a2—)Measurement₁₃ Report, as indicated in FIG. 8, at time t6. Thismeasurement and integration process repeats so that measurement reportsare obtained at times t4, t5, t6, t7, t8, . . . and so on, that is atapproximately the TDMA frame rate.

In the example of FIG. 10 where OR=⅓T and IL=6T, at times t0, t1, t2,t3, t4 and t5, each U_TCH signal is detected and measured by the hostand assistant BTS and each provides an integrated measurement report(IMR), namely, the U_(h—)Measurement_Report, theU_(a1)Measurement_Report and the U_(a2—)Measurement_Report, as indicatedin FIG. 8, at time t6. Similarly, at times t3, t4, t5 t6, t7 and t8,each U_TCH signal is detected and measured by the host and assistant BTSand each provides an integrated measurement report, namely, theU_(h—)Measurement_Report, the U_(a1—)Measurement_Report and theU_(a2)Measurement_Report, as indicated in FIG. 8, at time t9. Similarly,at times t6, t7, t8, t9, t10 and t11, each U_TCH signal is detected andmeasured by the host and assistant BTS and each provides an integratedmeasurement report, namely, the U_(h—)Measurement_Report, theU_(a1—)Measurement_Report and the U_(a2—)Measurement_Report, asindicated in FIG. 8, at time t12. This measurement and integrationprocess repeats so that measurement reports are obtained at times t6,t9, t12, t7, t16, . . . and so on, that is, approximately at one thirdthe TDMA frame rate. Note that at time t12, the U_SACCH burst is used inthe calculation as the equivalent of a U_TCH burst for purposes of themeasurement report since the U_TCH and U_SACCH have the same broadcastpower level. If signals of different power levels or other attributesare present, then the measurement algorithms of macrodiversity processor20 of FIG. 6 accommodate for the differences so that signals of likeproperties are processed.

In FIG. 10, the measurement reports, U_(h—)Measurement_Report,U_(a1—)Measurement_Report and U_(a2—)Measurement_Report are integratedmeasurement reports, generated by each zone manager measurement unit,transmitted to the _(h)ZM via the ZM-to-ZM links 14 of FIG. 6. Themacrodiversity processor 20, in FIG. 6, of the _(h)ZM compares thesemeasurement reports and decides which BS should be used to communicatedwith any particular MS for traffic and control. Before switching trafficor control over to an another one of the BS, the macrodiversityprocessor 20 consults with the resource manager 21 for availability ofradio resources in another one of the BS, for contentions with otherradio resource requests in that BS, and for availability of ZM-to-ZMlink bandwidth over links 14. Only after the resource manager 21 hasapproved the switch and after a radio resource has been reserved basedon availability and priority level and configured in the BS, is thetraffic or control switched over to the another one of the BS.

A number of different algorithms may be used by the macrodiversityprocessor 20 in the _(h)ZM to make the switching decisions. By way ofexample, the decision may be based on making a number k of measurementreport comparisons, where k is at least one. If after k such measurementreport comparisons, an alternate BS has a lower path loss or otherquality factor than the currently serving BS, than a switch is made tothe alternate BS.

Operation of the fast macrodiversity switching is explained inconnection with the following TABLE 1 which depicts the fastmacrodiversity switching as indicated in switching from the FIG. 2standard GSM configuration to a FIG. 3 configuration.

TABLE 1 gives an example of this decision process. In addition togenerating its own integrated measurement reports (IMR), the _(h)ZM inthe _(h)BS receives integrated measurement reports from three assistantBSs. The TABLE 1 lists a sequence of 17 such report intervals. The threecolumns in the center give sample values of these IMRs. As can be seenby the highlighted IMRs, at time step 4, _(a1)BS reports a higher value,16, than the _(h)BS value of 15. Assuming that a higher value isindicative of a better radio link to the MS, and assuming that twoconsecutive higher reports are used to effect a switch, the a decisionis made at time step 5 to switch the dedicated channels to _(a1)BS since_(a1)BS for the second consecutive time reports a higher value, 18, thanthe _(h)BS value of 14. As the MS continues to move, IMRs from _(a2)BSbecome larger. At time steps 15 and 16, the condition for twoconsecutive larger IMRs from _(a2)BS is fulfilled and the _(h)ZMswitches the dedicated channels over to _(a2)BS.

TABLE 1 IMR Sequence Switching at Rate _(h)BS _(a1)BTS _(a2)BTS _(a3)BTSDecision Basis OR IMR IMR IMR IMR k = 2 IMRs 1 25 11 6 3 2 25 14 5 3 318 15 4 2 4 15 16 4 1 5 14 18 3 1 Switch to _(a1)BTS 6 12 20 4 — 7 12 216 — 8 13 20 8 — 9 14 21 10 1 10 14 18 11 3 11 13 20 13 5 12 12 16 14 713 10 14 13 6 14 7 14 14 7 15 2 13 16 8 16 2 11 17 9 Switch to _(a2)BTS17 — 11 16 8

The switching decision algorithm may also take into account thedown-link measurement reports provided by the SACCH as shown in FIG. 8.For example, in a GSM network, these reports are available at 480 msintervals.

In FIG. 11, the _(h)BTS 12-1 and the corresponding _(h)ZM 13-1 are thehost BTS and the host BS 2-1 for the MS 4. The relationship between theBTS 12-1 and the MS 4 of FIG.11, however, is not like that for astandard GSM system. In FIG. 11, the traffic communication is ondedicated channels that have been switched to be between the assistant_(a1)BTS 12-2 in the assistant BS 2-2 and the MS 4 for the up-linktraffic, T_(U), on link 11 _(U) and has been switched to assistant_(aa)BTS 12-3 in the assistant BS 2-2 for the down-link traffic, T_(D),on link 11 _(D). The control channels include the down-link control,C_(D), on link 10 _(D1,2), and the up-link control, C_(U), on link 10_(U1,2).The down-link control channel, C_(D), has two components, adown-link broadcast control channel on link 10 _(D1) and a dedicateddown-link control channel on link 10 _(D2). The up-link control channel,C_(U), has two components, an up-link control channel on link 10 _(U1)and a dedicated up-link control channel on link 10 _(U2). The controlchannels, including the down-link control, C_(D), and the up-linkcontrol, C_(U), remain between host _(h)BTS 12-1 and MS 4. In the FIG.11 embodiment, the links 10 _(D1) and 10 _(D2) can be a common linksince they connect between the same resources. In other embodiments (seeFIG. 3), the control channel on link 10 _(D2) is switched as a dedicatedchannel. Although MS 4 is under control of the host _(h)BTS 12-1, theassistant BTSs including _(a1)BTS 12-2 and _(aa)BTS 12-3, associatedwith the assistant zone managers _(a1)ZM 13-2 and _(aa)ZM 13-3,participate directly for the traffic with MS 4.

In FIG. 12, the _(h)BTS 12-1 and the corresponding _(h)ZM 13-1 remain asthe host _(h)BTS and the host _(h)ZM forming the host BS 2-1 for the MS4. The relationship between the _(h)BTS 12-1 and the MS 4 of FIG. 12,however, is not like that for a standard GSM system. The trafficcommunication is on dedicated channels and has been switched between theassistant _(aa)BTS 12-3 and the MS 4 for the up-link traffic, T_(U), onlink 11 _(U) and also has been switched to assistant _(aa)BTS 12-3 forthe down-link traffic, T_(D), on link 11 _(D). The control channelsinclude the down-link control, C_(D), on link 10 _(D1,2), and theup-link control, C_(U), on link 10 _(U1,2). The down-link controlchannel, C_(D), has two components, a down-link broadcast controlchannel on link 10 _(D1) and a dedicated down-link control channel onlink 10 _(D2). The up-link control channel, C_(U), has two components,an up-link control channel on link 10 _(U1) and a dedicated up-linkcontrol channel on link 10 _(U2). The control channels, including thedown-link control, C_(D), and the up-link control, C_(U), remain betweenhost _(h)BTS 12-1 and MS 4. In the FIG. 11 embodiment, the links 10_(D1) and 10 _(D2) can be a common link since they connect between thesame resources. In other embodiments (see FIG. 3), the control channelon link 10 _(D2) is switched as dedicated channel. Although MS 4 isunder control of the host _(h)BTS 12-1, the assistant _(aa)BTS 12-3,associated with the assistant zone managers _(aa)ZM 13-3, participatesdirectly for the traffic with MS 4.

While the invention has been particularly shown and described withreference to preferred embodiments thereof it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the invention.

1. A communication system for communication using wireless signals, thesystem comprising: a plurality of transceiver stations configured totransmit and receive wireless signals over broadcast channels anddedicated channels, said wireless signals including down-link signals toand up-link signals from mobile stations; a plurality of measurementunits each configured to form measurements of said wireless signals; anda plurality of zone managers, various ones of which are connected to oneanother to form a zone network, wherein each zone manager, includes: aprocessor configured to process measurements formed by one or more ofsaid plurality of measurement units to determine preferred ones of saidplurality of transceiver stations for use in transmitting wirelesssignals associated with a particular mobile station over one or moreparticular dedicated channels, wherein transmission over the particulardedicated channels for the particular mobile station includes the use ofa first radio resource; and a control unit configured to dynamicallyswitch between said preferred ones of said plurality of transceiverstations during said transmitting wireless signals associated with theparticular mobile station over the one or more particular dedicatedchannels, wherein said dynamic switching occurs without changing thefirst radio resource.
 2. The communication system of claim 1, whereineach of said plurality of measurement units is configured to form saidmeasurements of said up-link signals from said particular mobilestation.
 3. The communication system of claim 1, wherein said dynamicswitching occurs in less than 1 second.
 4. The communication system ofclaim 1, wherein each of said plurality of zone managers is associatedwith a corresponding one of said plurality of transceiver stations. 5.The communication system of claim 4, wherein each of said plurality ofzone managers is co-located with its corresponding transceiver station.6. The communication system of claim 4, wherein two or more of saidplurality of zone managers are co-located.
 7. The communication systemof claim 6, wherein said two or more of said plurality of zone managersare co-located at a base station controller in a cellular system.
 8. Thecommunication system of claim 4, wherein said plurality of zone managersincludes one zone manager designated as a host zone manager for saidparticular mobile station and one or more additional ones of theplurality of zone managers designated as assistant zone managers forsaid particular mobile station, wherein said host zone manager isoperative to communicate over said particular broadcast channels withsaid particular mobile station while said particular dedicated channelsfor said particular mobile station are dynamically switched among saidone or more assistant zone managers and said host zone manager.
 9. Thecommunication system of claim 8, wherein each of said plurality ofmeasurement units is associated with a corresponding one of saidplurality of zone managers, wherein those ones of the plurality ofmeasurement units that are associated with said host and assistant zonemanagers are configured to form measurement of said up-link trafficsignals from said particular mobile station, wherein said measurementsinclude one or more of the following types of measurements: signalstrength measurements, error rate measurements, distance measurementsindicating a distance between the particular mobile station and one ofthe plurality of transceiver stations.
 10. The communication system ofclaim 9, wherein, each of said plurality of transceiver stationsinclude: one of a plurality of broadcasters configured to broadcast saiddown-link signals; and one of a plurality of collectors configured toreceive said up-link signals; wherein said processor of said host zonemanager is coupled to receive measurements from the one of the pluralityof measurement units associated with the host zone manager andconfigured to process said measurements to determine preferred ones ofsaid plurality of broadcasters and preferred ones of said plurality ofcollectors for said particular dedicated channels for communicationswith said particular mobile station; and wherein said control unit ofsaid host zone manager is configured to dynamically select saidparticular dedicated channels for said particular mobile station byselecting said preferred ones of said broadcasters to provide particulardown-link signals and said preferred ones of said collectors to receiveparticular up-link signals for said particular mobile station.
 11. Thecommunication system of claim 1, wherein each of said plurality of zonemanagers corresponds to one of said plurality of transceiver stations,wherein each of said plurality of zone managers includes: a resourcemanager configured to manage available resources in said communicationsystem; an airlink controller configured to control radio channels insaid communication system.
 12. The communication system of claim 11,wherein each of said plurality of zone managers includes a zonemanager-to-zone manager interface unit configured to provide aninterface to each of one or more other ones of the plurality of zonemanagers.
 13. The communication system of claim 11, wherein each of saidplurality of zone managers includes a transceiver interface configuredto provide an interface to its corresponding transceiver station. 14.The communication system of claim 11, wherein said communication systemincludes a controller link configured to provide an interface between abase station controller and a subset of said plurality of transceiverstations and said plurality of zone managers.
 15. The communicationsystem of claim 11, wherein one or more of said plurality of zonemanagers are integrated into one or more of said transceiver stations.16. The communication system of claim 1, wherein said control unit isconfigured to issue: broadcaster commands for controlling the down-linksignals to a first set of said mobile stations, and collector commandsfor controlling a plurality of collectors for changing the up-linksignals for each of a second set of said mobile stations, wherein noneof said first set of said mobile stations is in said second set of saidmobile stations and vice versa.
 17. The communication system of claim 1,wherein said wireless signals employ multiple access protocols.
 18. Thecommunication system of claim 17, wherein said multiple access protocolsinclude one or more of the following protocols: TDMA, CDMA, SDMA, andFDMA.
 19. The communication system of claim 1, wherein each of saidplurality of transceiver stations is configured to communicate over aregion containing one or more zones, and wherein said measurementsformed by said plurality of measurement units includes measurements ofwireless signals received by one or more collectors in each of saidplurality of transceiver stations.
 20. The communication system of claim19, wherein said measurements from said one or more collectors in eachof said plurality of transceiver stations include indications of radiolink conditions between a mobile station and said one or morecollectors.
 21. The communication system of claim 20, wherein said radiolink conditions include one or more of the following: path loss, forwarderror rates, carrier to interference ratio.
 22. The communication systemof claim 1, wherein said plurality of zone managers includes a host zonemanager and one or more assistant zone managers and wherein said hostzone manager is configured to process said measurements from the one ormore assistant zone managers to derive processor information fordetermining said preferred ones of said plurality of transceiverstations.
 23. The communication system of claim 22, wherein saidprocessor information includes one or more of the following types ofinformation: priority levels for the communication links with mobilestations, timing and synchronization information, transmit power level,locations of mobile stations.
 24. The communication system of claim 1,wherein each of said plurality of transceiver stations includebroadcaster controllers configured to control broadcaster transmittersand further configured to select one or more broadcaster transmittersfor forward communications with mobile stations.
 25. A method,comprising: transmitting, from a plurality of transceiver stations,downlink wireless signals over broadcast channels and dedicatedchannels; receiving, at said plurality of transceiver stations, uplinkwireless signals transmitted from mobile stations; forming measurementsof said unlink wireless signals; processing said measurements todetermine preferred ones of said transceiver stations for particulardedicated channels for a particular mobile station; and dynamicallyswitching between said preferred ones of said plurality of transceiverstations during transmitting downlink wireless signals to saidparticular mobile station, wherein a radio resource used for saidparticular dedicated channels for said particular mobile station remainsunchanged as a result of said dynamically switching.
 26. The method ofclaim 25, further comprising measuring said up-link signals from saidparticular mobile station to form said measurements.
 27. The method ofclaim 25, wherein said dynamically switching occurs in less than onesecond.
 28. A communication system for providing wireless communicationswith mobile devices, the system comprising: a plurality of transceiverstations configured to communicate with mobile devices, wherein each ofthe plurality of transceiver stations is configured to communicate viabroadcast channels and dedicated channels, wherein one of the pluralityof transceiver stations is designated as a host transceiver station fora first mobile device, and wherein the host transceiver is configured toprovide the broadcast channels for communication with the first mobiledevice; and a plurality of processors each associated with acorresponding one of said plurality of transceiver stations, to whereinone of the plurality of processors associated with the host transceiverstation is configured to act as a host zone manager for the first mobiledevice, wherein the processor associated with the host zone manager isconfigured to dynamically switch between selected ones of the pluralityof transceiver stations to provide the dedicated channels forcommunications with the first mobile device, wherein the dynamicswitching does not affect the host transceiver providing the broadcastchannels, and wherein a radio resource used for the dedicated channelsfor the first mobile device remains unchanged as a result of the dynamicswitching.
 29. The system of claim 28, wherein said processor associatedwith the host zone manager is configured to: receive signal measurementsfrom at least a subset of said plurality of processors, wherein thesignal measurements are measurements of up-link signals from the firstmobile station; process the received signal measurements in order toform processed signal measurements; and dynamically switch between theselected ones of the plurality of transceiver stations based on theprocessed signal measurements to provide the dedicated channels for thefirst mobile device.
 30. The system of claim 28, wherein the system isconfigured such that a first set of the plurality of transceiverstations is configured to provide uplink communications with the firstmobile device and a second set of the plurality of transceiver stationsis configured to provide downlink communications with the first mobiledevice.
 31. The system of claim 28, wherein a first subset of theplurality of transceiver stations is configured to provide trafficsignals to the first mobile device and a second subset of the pluralityof transceiver stations is configured to provide control signals to thefirst mobile device.
 32. A method of operating a communication systemusing wireless down-link signals to and wireless up-link signals frommobile stations, comprising: dynamically switching between preferredones of a plurality of transceivers to provide particular dedicatedchannels for a particular mobile station; and separately providingparticular broadcast channels for said particular mobile station fromanother one of said plurality of transceivers; wherein a radio resourceused to provide the particular dedicated channels remains unchanged as aresult of the dynamic switching between the preferred ones of theplurality of transceivers.